Coronavirus, inexplicable hysteria
Otherwise rational and intelligent people, of late, have become unhinged by otherwise normal behaviour. Here's an example. A colleague and friend who works at a prestigious university (and has a PhD) has been spreading rumours about how the coronavirus spreads. According to the person's social media accounts, the virus spreads not by water droplets in one's respiration but by air, much akin to the measles. When a person emits sounds or breathes, the virus floats freely into the air until it reaches a human surface. Obviously, this rumour is unequivocally FALSE. Here's why: if the virus spread was airborne, the rate of infection would be exponentially higher than it is. Airborne spread tends to infect whole communities in a few hours, rather than a few days or months.
Some of this person's friends have fueled my colleague's vicious rumours by protesting against people's "selfish" behaviour during the Pandemic. They have seen people walking through the neighbourhood without wearing a mask or protective covering. My colleague responded positively to the comment by bearing witness to a neighbour who dared to walk by my colleague's house and speak loudly with the others who were walking with the neighbour. My colleague was concerned that the water droplets from the person's speaking on the roadway would float freely through the air and reach my colleague's nose or mouth, even though my colleague was 25 to 30 metres from the neighbour who dared to speak while walking down the roadway.
This is a classic example of epistemic arrogance and trespassing. First, my colleague does not possess any willingness to see others' views as an improvement upon their own epistemic situation. Since, perhaps, my colleague is a university lecturer and since that may give my colleague some licence not to take others' seriously, this seems to be a classic example of epistemic arrogance. Moreover, it's an instance of trespassing because my colleague is neither a medical practitioner nor an epidemiologist or microbiologist--specialists who would quite easily be able to provide guidance in the matters about which my colleague is offering an opinion.
Is coronavirus airborne? Admittedly, the empirical evidence for it being airborne is not clear. An article published in Nature, e.g., concluded that evidence is mixed (here). While the virus may be aerosolised, there is scant evidence that it is airborne in the same way that other ailments may be so, such as measles. There is a difference between "being aerosolised" and breathing, by the way, that few people understand. Breathing may cause an infection because of the water droplets in normal respiration (here;here). Being airborne means that the virus remains suspended in the air for a duration of time and, if the virus is aerosolised, the virus is a mere 5 microns across. In a letter to the editor of the New England Journal of Medicine, Dorelman et al. wrote that they believed the virus may be suspended in air for upwards of 8 hours. Their experiment, however, was performed in a lab-controlled environment and included the use of a nebulisor, whose main purpose is to keep water droplets, dust particles, and anything else like viruses airborne.
An unreviewed manuscript produced by Liu and colleagues argue that there is some evidence that coronavirus is airborne, since they discovered viral RNA of COVID-19 in department stores and "during breathing or talking, SARS-CoV-2 aerosol transmission might occur and impact people both near and far from the source" (here). Among their recommendations, they included that the public ought to wear masks to prevent infection. (note bene: This is a rather dangerous recommendation because there is NO evidence in the medical literature that suggests wearing a mask will prevent infection; it is merely the case that a mask will prevent a symptomatic or asymptomatic individual from shedding the virus to someone else who is nearby.)
Another study published in the Journal of the American Medical Association Research Letters showed that there was little evidence of the virus being aerosolised (here). In the study conducted by Ong et al., there was no evidence that the virus was airborne, and any evidence there was of its begin aerosolised came from environments that could have been contaminated by coughs and sneezes from COVID-19 patients who were nearby. This study has been supported by a study completed by Lydia Bourouiba (here), but one of her other potentially disturbing conclusions was that the virus may spread to people who are greater than 2m away from any infected individual who has sneezed or coughed.
A similar study published by researchers in Nebraska found viral RNA in 2/3 of the air samples collected in isolation rooms in a hospital treating COVID-19 patients and in a quarantine facility housing people who had contracted a mild form of coronavirus (here).
For each of the studies, however, there are some important facts that must be kept in mind when we "err on the side of caution" and recommend wearing masks or other personal protective gear when we are in public. First, there is NO evidence that the air samples collected had enough viral load to infect a patient. Even if a person's regular respiration patterns in breathing produce a viral load, there is no evidence that breathing will yield infection to someone who is standing 10m or greater from the person who is breathing. One may believe that the situation is different where a person has sneezed or coughed. Again, if the water droplets are small enough, it is unclear whether they could carry a viral load large enough to infect another person. Second, there is a question over what size water droplet is required for viral load to be infectious to others in the vicinity--even if the persons may be greater than 2m (6-feet) away. Perhaps there has to be water droplets with great enough volume to carry the viral load and infect others. Finally, the length of time one is exposed to the virus may be an important factor in becoming infected. If a infected person crosses paths with a healthy person and the exposure time is limited, then the healthy person may not become infected. Even if the healthy person is exposed to a number of different people on different occasions, it is unclear whether that alone will permit the virus to infect the healthy person.
Here's the way that I think about matters. Unless one's colleague is an epidemiologist or medical practitioner or researcher with great experience, do not take the person's word for it. Yes, the person may be quite skilled at reading, may be quite skilled at his or her own area of expertise. I do not doubt that, but I doubt that that person's specialisation carries over to medicine. Let's rely upon the experts' views here, let's not carry conversations over social media that shame or bash others for doing or not doing what one expects them to do. It is that sort of behaviour that leads to hysteria, anxiety, and fear among friends and colleagues.
Focus on the facts, go out there and read what you can from reputable sources, and share what you may. The facts will permit us to make the right decision about how to move forward with our lives, despite the virus.